Fixed #20931 -- Fixed select widgets nested choice rendering

ChoiceFieldRenderer was not rendering nested choices. Added recursion
to ChoiceFieldRenderer to take nested choices and render them as
<ul>'s.

AUTHORS

@@ -89,6 +89,7 @@ answer newbie questions, and generally made Django that much better:
     David Avsajanishvili <avsd05@gmail.com>
     Mike Axiak <axiak@mit.edu>
     Niran Babalola <niran@niran.org>
+    Christopher Babiak <chrisbabiak@gmail.com>
     Vitaly Babiy <vbabiy86@gmail.com>
     Morten Bagai <m@bagai.com>
     Jeff Balogh <jbalogh@mozilla.com>

django/forms/widgets.py

@@ -665,10 +665,6 @@ class ChoiceFieldRenderer(object):
         self.attrs = attrs
         self.choices = choices
 
-    def __iter__(self):
-        for i, choice in enumerate(self.choices):
-            yield self.choice_input_class(self.name, self.value, self.attrs.copy(), choice, i)
-
     def __getitem__(self, idx):
         choice = self.choices[idx] # Let the IndexError propogate
         return self.choice_input_class(self.name, self.value, self.attrs.copy(), choice, idx)
@@ -685,8 +681,23 @@ class ChoiceFieldRenderer(object):
         id_ = self.attrs.get('id', None)
         start_tag = format_html('<ul id="{0}">', id_) if id_ else '<ul>'
         output = [start_tag]
-        for widget in self:
+        for i, choice in enumerate(self.choices):
-            output.append(format_html('<li>{0}</li>', force_text(widget)))
+            choice_value, choice_label = choice
+            if isinstance(choice_label, (tuple,list)):
+                attrs_plus = self.attrs.copy()
+                if id_:
+                    attrs_plus['id'] += '_{0}'.format(i)
+                sub_ul_renderer = ChoiceFieldRenderer(name=self.name,
+                                                      value=self.value,
+                                                      attrs=attrs_plus,
+                                                      choices=choice_label)
+                sub_ul_renderer.choice_input_class = self.choice_input_class
+                output.append(format_html('<li>{0}{1}</li>', choice_value,
+                                          sub_ul_renderer.render()))
+            else:
+                w = self.choice_input_class(self.name, self.value,
+                                            self.attrs.copy(), choice, i)
+                output.append(format_html('<li>{0}</li>', force_text(w)))
         output.append('</ul>')
         return mark_safe('\n'.join(output))
 

tests/forms_tests/tests/test_widgets.py

@@ -695,6 +695,37 @@ beatle J R Ringo False""")
 <li><label for="bar_1"><input type="radio" id="bar_1" value="P" name="beatle" /> Paul</label></li>
 <li><label for="bar_2"><input type="radio" id="bar_2" value="G" name="beatle" /> George</label></li>
 <li><label for="bar_3"><input type="radio" id="bar_3" value="R" name="beatle" /> Ringo</label></li>
+</ul>""")
+
+    def test_nested_choices(self):
+        # Choices can be nested for radio buttons:
+        w = RadioSelect()
+        w.choices=(('unknown', 'Unknown'), ('Audio', (('vinyl', 'Vinyl'), ('cd', 'CD'))), ('Video', (('vhs', 'VHS'), ('dvd', 'DVD'))))
+        self.assertHTMLEqual(w.render('nestchoice', 'dvd', attrs={'id':'media'}), """<ul id="media">
+<li><label for="media_0"><input id="media_0" name="nestchoice" type="radio" value="unknown" /> Unknown</label></li>
+<li>Audio<ul id="media_1">
+<li><label for="media_1_0"><input id="media_1_0" name="nestchoice" type="radio" value="vinyl" /> Vinyl</label></li>
+<li><label for="media_1_1"><input id="media_1_1" name="nestchoice" type="radio" value="cd" /> CD</label></li>
+</ul></li>
+<li>Video<ul id="media_2">
+<li><label for="media_2_0"><input id="media_2_0" name="nestchoice" type="radio" value="vhs" /> VHS</label></li>
+<li><label for="media_2_1"><input checked="checked" id="media_2_1" name="nestchoice" type="radio" value="dvd" /> DVD</label></li>
+</ul></li>
+</ul>""")
+
+        # Choices can be nested for checkboxes:
+        w = CheckboxSelectMultiple()
+        w.choices=(('unknown', 'Unknown'), ('Audio', (('vinyl', 'Vinyl'), ('cd', 'CD'))), ('Video', (('vhs', 'VHS'), ('dvd', 'DVD'))))
+        self.assertHTMLEqual(w.render('nestchoice', ('vinyl', 'dvd'), attrs={'id':'media'}), """<ul id="media">
+<li><label for="media_0"><input id="media_0" name="nestchoice" type="checkbox" value="unknown" /> Unknown</label></li>
+<li>Audio<ul id="media_1">
+<li><label for="media_1_0"><input checked="checked" id="media_1_0" name="nestchoice" type="checkbox" value="vinyl" /> Vinyl</label></li>
+<li><label for="media_1_1"><input id="media_1_1" name="nestchoice" type="checkbox" value="cd" /> CD</label></li>
+</ul></li>
+<li>Video<ul id="media_2">
+<li><label for="media_2_0"><input id="media_2_0" name="nestchoice" type="checkbox" value="vhs" /> VHS</label></li>
+<li><label for="media_2_1"><input checked="checked" id="media_2_1" name="nestchoice" type="checkbox" value="dvd" /> DVD</label></li>
+</ul></li>
 </ul>""")
 
     def test_checkboxselectmultiple(self):